MIT Technology Review

Wednesday, June 04, 2014

A Cleaner, Cheaper Way to Make Metals

A startup called Infinium promises to reduce a troubling source of carbon emissions.

In lab space across from a yoga studio in an office park in Natick, Massachusetts, Adam Powell holds up a brilliant white ceramic tube that he says is the key to making the production of many widely used metals significantly cheaper and less polluting.

Powell is the chief technology officer of Infinium, a startup spun out of Boston University that’s been operating quietly since 2008 and is now ready to go to market with its first products—the “rare earth” metals neodymium and dysprosium. These materials are needed to make powerful magnets that work at high temperatures and are important for the generators found in wind turbines and many electric car motors.  

While Infinium’s approach can be used to produce other metals, including magnesium and aluminum, the company is starting with rare earths because they fetch much higher prices. Its first customer is the U.S. government, which needs rare earth metals for its stockpile of strategically valuable materials. Rare earth ore is mined in just a few places in the world, and high costs and environmental challenges have prevented companies from processing rare earth ore to make metals domestically.

Infinium’s process addresses a specific part of metal production: transforming partially processed ores—metal oxides—into metals. This can be done by immersing the oxides in a bath of molten salt and running electricity through the mixture. Aside from the emissions associated with generating that power, this process itself releases greenhouse gases. One of the electrodes is usually made of carbon, which reacts with oxygen, forming carbon dioxide.

The ceramic material Powell showed me—which is made of zirconium oxide—replaces the carbon electrode and eliminates those emissions. Researchers have been trying to replace carbon for many years, but the molten salts have corroded the alternatives. The key advance for Infinium was developing alternative molten salts that don’t react with the zirconium oxide, so that it can last long enough to be practical.

This month Infinium is starting up production using a machine that will produce half a ton of rare earth metals annually. In September, Infinium will start using another machine that can produce 10 metric tons a year—enough for the company to be profitable, Powell says. Infinium has also demonstrated that the process works for aluminum, magnesium, titanium, and silicon, and it plans to scale up production of the first two of those by 2016.

The process isn’t a cure-all for the environmental problems associated with metal production. It doesn’t address pollution from mining and separating rare earth oxides from other materials in the ore (other new processes are being developed to address those issues—see “The Rare-Earth Crisis”).

But for metals such as aluminum and magnesium, Infinium says, it can reduce processing costs by 30 to 50 percent. Making these metals much cheaper could, for one thing, transform car-making. Parts made of these metals weigh far less than the steel parts ordinarily used in cars, while being just as strong. The weight savings could reduce fuel consumption by 10 percent, according to an auto industry consortium.

As the company scales up production, one key question will be whether its ceramic electrodes hold up for as long as the company’s smaller-scale testing suggests they will. If the ceramic doesn’t last, the company may not have a cost advantage.

Finding an alternative to carbon has long been the “dream” of the metals industry, says Donald Sadoway, a professor of materials science at MIT who is not involved with the company. “I believe [Infinium’s] technology is sound. It’s real,” he says. Whether the company succeeds “is all about the economics,” he says. “No one cares about the flow chart for the process. You care about the prices. If it produces a good metal at a lower cost, people will be interested.”